1. Field of the Invention
The invention relates to a roll-up door assembly of the type commonly used in a trailer for a semi-tractor or a truck. In one of its aspects, the invention relates to a lightweight roll-up door comprising multiple, longitudinally-oriented extruded panels having a longitudinal hinge axis that can be assembled transversely relative to the hinge axis. In another of its aspects, the invention relates to an extruded panel for a roll-up door, which includes an integrated mounting and guide system for positioning and attaching door hardware to the panel.
2. Description of the Related Art
Trailers for semi-tractors and delivery trucks have long used roll-up doors to control access through a rear opening of the trailer. Roll-up doors are often preferred over the vertically-hinged, outwardly swinging doors because the roll-up doors operate within the physical space of the trailer and do not require space beyond the trailer. The roll-up door is moveable between an opened and a closed position while being maintained entirely within the trailer whereas the swinging doors require room along the sides of the trailer to swing from the closed to the opened position. If the trailers are to be parked side-by-side, the swinging doors must be opened prior to parking the trailer or the trailers must be parked far enough apart to permit the doors to swing from the closed to the opened position, both of which are an inconvenience to the operator.
Roll-up doors typically comprise multiple panels, stacked one atop the other. The adjacent edges are hingedly connected together to form the entire door. The hinges are normally located on or near the adjacent longitudinal edges of the panels. There are generally two main types of hinged structures that can be categorized by the direction in which the panels must be assembled relative to the longitudinal axis of the panels. One hinge structure requires that the panels be slid laterally (in the same direction as the longitudinal axis) to hingedly couple/uncouple the panels. Another structure requires that the panels be moved to transversely or perpendicular to the longitudinal edge to hingedly couple/uncouple the panels.
Each panel usually includes a roller assembly comprising an axle that rotatably supports a roller or wheel. The axle is mounted to the panel, directly or through the hinge assembly. The wheel is received within a track mounted within the interior of the trailer. As the door is raised from the lowered or closed position to the raised or opened position, the panels move within the tracks and rotate relative to each other as needed about their respective hinges. The panels are constrained in their movement by the receipt of the rollers within the track. Thus, the maximum angle of rotation between any two panels can be controlled by the arc of the track.
Roll-up doors have several known problems or disadvantages. Many roll-up doors have panels that are made entirely of solid material, such as wood. The resulting door is exceptionally heavy and requires counter-balancing springs to lift and close the door. The counter-balancing springs reduce the usable volume of the trailer, which is highly undesirable given the great value placed upon usable volume for a truck or trailer.
Attempts to address this problem have focused on using lighter weight materials, especially extruded plastics. The resulting extruded panels are relative light in weight, but they often require special or complex hinge systems and special structural stiffening to accommodate the mounting of the roll-up door hardware such as handles and latch assemblies.
Many roll-up doors are often time-consuming to repair. When a roll-up door is damaged, usually the repair is affected by merely replacing one of the multiple panels. Unfortunately, most roll-up doors have a panel and hinge configuration that requires the removal of multiple or all of the panels to replace the damaged panel. Panels that have hinges that require the lateral sliding of the panels for assembly further exacerbate the replacement of a single panel in that all of the panels preceding the damaged panel must be removed from the tracks before the damaged panel can be laterally slid and uncoupled from the adjacent panels.
Solutions to this problem have tended to focus on hinge structures that permit the transverse addition/removal of the panels. Most of the current solutions rely on a relatively complex hinge construction to permit the transverse removal of the hinge as part of the transverse removal of the panel.